man/systemd.network.xml

   1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   This file is part of systemd.
   7
   8   Copyright 2013 Tom Gundersen
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  23
  24 <refentry id="systemd.network" conditional='ENABLE_NETWORKD'>
  25
  26   <refentryinfo>
  27     <title>systemd.network</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>Developer</contrib>
  33         <firstname>Tom</firstname>
  34         <surname>Gundersen</surname>
  35         <email>teg@jklm.no</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>systemd.network</refentrytitle>
  42     <manvolnum>5</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>systemd.network</refname>
  47     <refpurpose>Network configuration</refpurpose>
  48   </refnamediv>
  49
  50   <refsynopsisdiv>
  51     <para><filename><replaceable>network</replaceable>.network</filename></para>
  52   </refsynopsisdiv>
  53
  54   <refsect1>
  55     <title>Description</title>
  56
  57     <para>Network setup is performed by
  58     <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  59     </para>
  60
  61     <para>Network files must have the extension
  62     <filename>.network</filename>; other extensions are ignored.
  63     Networks are applied to links whenever the links appear.</para>
  64
  65     <para>The <filename>.network</filename> files are read from the
  66     files located in the system network directory
  67     <filename>/usr/lib/systemd/network</filename>, the volatile
  68     runtime network directory
  69     <filename>/run/systemd/network</filename> and the local
  70     administration network directory
  71     <filename>/etc/systemd/network</filename>. All configuration files
  72     are collectively sorted and processed in lexical order, regardless
  73     of the directories in which they live. However, files with
  74     identical filenames replace each other. Files in
  75     <filename>/etc</filename> have the highest priority, files in
  76     <filename>/run</filename> take precedence over files with the same
  77     name in <filename>/usr/lib</filename>. This can be used to
  78     override a system-supplied configuration file with a local file if
  79     needed. As a special case, an empty file (file size 0) or symlink
  80     with the same name pointing to <filename>/dev/null</filename>
  81     disables the configuration file entirely (it is "masked").</para>
  82
  83     <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6 nor IPv6LL enabled,
  84     shall be considered to have no IPv6 support. IPv6 will be automatically disabled for that interface by writing "1"
  85     to <filename>/proc/sys/net/ipv6/conf/<replaceable>ifname</replaceable>/disable_ipv6</filename>.
  86     </para>
  87   </refsect1>
  88
  89   <refsect1>
  90     <title>[Match] Section Options</title>
  91
  92       <para>The network file contains a <literal>[Match]</literal>
  93       section, which determines if a given network file may be applied
  94       to a given device; and a <literal>[Network]</literal> section
  95       specifying how the device should be configured. The first (in
  96       lexical order) of the network files that matches a given device
  97       is applied, all later files are ignored, even if they match as
  98       well.</para>
  99
 100       <para>A network file is said to match a device if each of the
 101       entries in the <literal>[Match]</literal> section matches, or if
 102       the section is empty. The following keys are accepted:</para>
 103
 104       <variablelist class='network-directives'>
 105         <varlistentry>
 106           <term><varname>MACAddress=</varname></term>
 107           <listitem>
 108             <para>The hardware address of the interface (use full colon-delimited hexadecimal, e.g.,
 109             01:23:45:67:89:ab).</para>
 110           </listitem>
 111         </varlistentry>
 112         <varlistentry>
 113           <term><varname>Path=</varname></term>
 114           <listitem>
 115             <para>A whitespace-separated list of shell-style globs
 116             matching the persistent path, as exposed by the udev
 117             property <literal>ID_PATH</literal>.</para>
 118           </listitem>
 119         </varlistentry>
 120         <varlistentry>
 121           <term><varname>Driver=</varname></term>
 122           <listitem>
 123             <para>A whitespace-separated list of shell-style globs
 124             matching the driver currently bound to the device, as
 125             exposed by the udev property <literal>DRIVER</literal>
 126             of its parent device, or if that is not set the driver
 127             as exposed by <literal>ethtool -i</literal> of the
 128             device itself.</para>
 129           </listitem>
 130         </varlistentry>
 131         <varlistentry>
 132           <term><varname>Type=</varname></term>
 133           <listitem>
 134             <para>A whitespace-separated list of shell-style globs
 135             matching the device type, as exposed by the udev property
 136             <literal>DEVTYPE</literal>.</para>
 137           </listitem>
 138         </varlistentry>
 139         <varlistentry>
 140           <term><varname>Name=</varname></term>
 141           <listitem>
 142             <para>A whitespace-separated list of shell-style globs
 143             matching the device name, as exposed by the udev property
 144             <literal>INTERFACE</literal>.</para>
 145           </listitem>
 146         </varlistentry>
 147         <varlistentry>
 148           <term><varname>Host=</varname></term>
 149           <listitem>
 150             <para>Matches against the hostname or machine ID of the
 151             host. See <literal>ConditionHost=</literal> in
 152             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 153             for details.
 154             </para>
 155           </listitem>
 156         </varlistentry>
 157         <varlistentry>
 158           <term><varname>Virtualization=</varname></term>
 159           <listitem>
 160             <para>Checks whether the system is executed in a virtualized
 161             environment and optionally test whether it is a specific
 162             implementation. See <literal>ConditionVirtualization=</literal> in
 163             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 164             for details.
 165             </para>
 166           </listitem>
 167         </varlistentry>
 168         <varlistentry>
 169           <term><varname>KernelCommandLine=</varname></term>
 170           <listitem>
 171             <para>Checks whether a specific kernel command line option is
 172             set (or if prefixed with the exclamation mark unset). See
 173             <literal>ConditionKernelCommandLine=</literal> in
 174             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 175             for details.
 176             </para>
 177           </listitem>
 178         </varlistentry>
 179         <varlistentry>
 180           <term><varname>Architecture=</varname></term>
 181           <listitem>
 182             <para>Checks whether the system is running on a specific
 183             architecture. See <literal>ConditionArchitecture=</literal> in
 184             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 185             for details.
 186             </para>
 187           </listitem>
 188         </varlistentry>
 189       </variablelist>
 190
 191   </refsect1>
 192
 193   <refsect1>
 194     <title>[Link] Section Options</title>
 195
 196     <para> The <literal>[Link]</literal> section accepts the following keys:</para>
 197
 198     <variablelist class='network-directives'>
 199       <varlistentry>
 200         <term><varname>MACAddress=</varname></term>
 201         <listitem>
 202           <para>The hardware address to set for the device.</para>
 203         </listitem>
 204       </varlistentry>
 205       <varlistentry>
 206         <term><varname>MTUBytes=</varname></term>
 207         <listitem>
 208           <para>The maximum transmission unit in bytes to set for the
 209           device. The usual suffixes K, M, G, are supported and are
 210           understood to the base of 1024.</para>
 211           <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
 212           below 1280 (the minimum MTU for IPv6) it will automatically be increased to this value.</para>
 213         </listitem>
 214       </varlistentry>
 215     </variablelist>
 216   </refsect1>
 217
 218   <refsect1>
 219     <title>[Network] Section Options</title>
 220
 221       <para>The <literal>[Network]</literal> section accepts the following keys:</para>
 222
 223       <variablelist class='network-directives'>
 224         <varlistentry>
 225           <term><varname>Description=</varname></term>
 226           <listitem>
 227             <para>A description of the device. This is only used for
 228             presentation purposes.</para>
 229           </listitem>
 230         </varlistentry>
 231         <varlistentry>
 232           <term><varname>DHCP=</varname></term>
 233           <listitem>
 234             <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
 235             <literal>yes</literal>, <literal>no</literal>,
 236             <literal>ipv4</literal>, or <literal>ipv6</literal>.</para>
 237
 238             <para>Note that DHCPv6 will by default be triggered by Router
 239             Advertisement, if that is enabled, regardless of this parameter.
 240             By enabling DHCPv6 support explicitly, the DHCPv6 client will
 241             be started regardless of the presence of routers on the link,
 242             or what flags the routers pass. See
 243             <literal>IPv6AcceptRA=</literal>.</para>
 244
 245             <para>Furthermore, note that by default the domain name
 246             specified through DHCP is not used for name resolution.
 247             See option <option>UseDomains=</option> below.</para>
 248
 249             <para>See the <literal>[DHCP]</literal> section below for further configuration options for the DHCP client
 250             support.</para>
 251           </listitem>
 252         </varlistentry>
 253         <varlistentry>
 254           <term><varname>DHCPServer=</varname></term>
 255           <listitem>
 256             <para>A boolean. Enables DHCPv4 server support. Defaults
 257             to <literal>no</literal>. Further settings for the DHCP
 258             server may be set in the <literal>[DHCPServer]</literal>
 259             section described below.</para>
 260           </listitem>
 261         </varlistentry>
 262         <varlistentry>
 263           <term><varname>LinkLocalAddressing=</varname></term>
 264           <listitem>
 265             <para>Enables link-local address autoconfiguration. Accepts
 266             <literal>yes</literal>, <literal>no</literal>,
 267             <literal>ipv4</literal>, or <literal>ipv6</literal>. Defaults to
 268             <literal>ipv6</literal>.</para>
 269           </listitem>
 270         </varlistentry>
 271         <varlistentry>
 272           <term><varname>IPv4LLRoute=</varname></term>
 273           <listitem>
 274             <para>A boolean. When true, sets up the route needed for
 275             non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
 276             to false.
 277             </para>
 278           </listitem>
 279         </varlistentry>
 280         <varlistentry>
 281           <term><varname>IPv6Token=</varname></term>
 282           <listitem>
 283             <para>An IPv6 address with the top 64 bits unset. When set, indicates the
 284             64-bit interface part of SLAAC IPv6 addresses for this link. Note that
 285             the token is only ever used for SLAAC, and not for DHCPv6 addresses, even
 286             in the case DHCP is requested by router advertisement. By default, the
 287             token is autogenerated.</para>
 288           </listitem>
 289         </varlistentry>
 290         <varlistentry>
 291           <term><varname>LLMNR=</varname></term>
 292           <listitem>
 293             <para>A boolean or <literal>resolve</literal>. When true,
 294             enables <ulink
 295             url="https://tools.ietf.org/html/rfc4795">Link-Local
 296             Multicast Name Resolution</ulink> on the link. When set to
 297             <literal>resolve</literal>, only resolution is enabled,
 298             but not host registration and announcement. Defaults to
 299             true. This setting is read by
 300             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 301           </listitem>
 302         </varlistentry>
 303         <varlistentry>
 304           <term><varname>MulticastDNS=</varname></term>
 305           <listitem>
 306             <para>A boolean or <literal>resolve</literal>. When true,
 307             enables <ulink
 308             url="https://tools.ietf.org/html/rfc6762">Multicast
 309             DNS</ulink> support on the link. When set to
 310             <literal>resolve</literal>, only resolution is enabled,
 311             but not host or service registration and
 312             announcement. Defaults to false. This setting is read by
 313             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 314           </listitem>
 315         </varlistentry>
 316         <varlistentry>
 317           <term><varname>DNSSEC=</varname></term>
 318           <listitem>
 319             <para>A boolean or
 320             <literal>allow-downgrade</literal>. When true, enables
 321             <ulink
 322             url="https://tools.ietf.org/html/rfc4033">DNSSEC</ulink>
 323             DNS validation support on the link. When set to
 324             <literal>allow-downgrade</literal>, compatibility with
 325             non-DNSSEC capable networks is increased, by automatically
 326             turning off DNSEC in this case. This option defines a
 327             per-interface setting for
 328             <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
 329             global <varname>DNSSEC=</varname> option. Defaults to
 330             false. This setting is read by
 331             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 332           </listitem>
 333         </varlistentry>
 334         <varlistentry>
 335           <term><varname>DNSSECNegativeTrustAnchors=</varname></term>
 336           <listitem><para>A space-separated list of DNSSEC negative
 337           trust anchor domains. If specified and DNSSEC is enabled,
 338           look-ups done via the interface's DNS server will be subject
 339           to the list of negative trust anchors, and not require
 340           authentication for the specified domains, or anything below
 341           it. Use this to disable DNSSEC authentication for specific
 342           private domains, that cannot be proven valid using the
 343           Internet DNS hierarchy. Defaults to the empty list. This
 344           setting is read by
 345           <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 346           </listitem>
 347         </varlistentry>
 348         <varlistentry>
 349           <term><varname>LLDP=</varname></term>
 350           <listitem>
 351             <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
 352             implemented on professional routers and bridges which announces which physical port a system is connected
 353             to, as well as other related data. Accepts a boolean or the special value
 354             <literal>routers-only</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
 355             neighbors maintained. If <literal>routers-only</literal> is set only LLDP data of various types of routers
 356             is collected and LLDP data about other types of devices ignored (such as stations, telephones and
 357             others). If false, LLDP reception is disabled. Defaults to <literal>routers-only</literal>. Use
 358             <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
 359             collected neighbor data. LLDP is only available on Ethernet links. See <varname>EmitLLDP=</varname> below
 360             for enabling LLDP packet emission from the local system.
 361             </para>
 362           </listitem>
 363         </varlistentry>
 364         <varlistentry>
 365           <term><varname>EmitLLDP=</varname></term>
 366           <listitem>
 367             <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
 368             <literal>nearest-bridge</literal>, <literal>non-tpmr-bridge</literal> and
 369             <literal>customer-bridge</literal>.  Defaults to false, which turns off LLDP packet emission. If not false,
 370             a short LLDP packet with information about the local system is sent out in regular intervals on the
 371             link. The LLDP packet will contain information about the local host name, the local machine ID (as stored
 372             in <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
 373             local interface name, as well as the pretty hostname of the system (as set in
 374             <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
 375             emission is only available on Ethernet links. Note that this setting passes data suitable for
 376             identification of host to the network and should thus not be enabled on untrusted networks, where such
 377             identification data should not be made available. Use this option to permit other systems to identify on
 378             which interfaces they are connected to this system. The three special values control propagation of the
 379             LLDP packets. The <literal>nearest-bridge</literal> setting permits propagation only to the nearest
 380             connected bridge, <literal>non-tpmr-bridge</literal> permits propagation across Two-Port MAC Relays, but
 381             not any other bridges, and <literal>customer-bridge</literal> permits propagation until a customer bridge
 382             is reached. For details about these concepts, see <ulink
 383             url="http://standards.ieee.org/getieee802/download/802.1AB-2009.pdf">IEEE 802.1AB-2009</ulink>. Note that
 384             configuring this setting to true is equivalent to <literal>nearest-bridge</literal>, the recommended and
 385             most restricted level of propagation. See <varname>LLDP=</varname> above for an option to enable LLDP
 386             reception.</para>
 387           </listitem>
 388         </varlistentry>
 389         <varlistentry>
 390           <term><varname>BindCarrier=</varname></term>
 391           <listitem>
 392             <para>A link name or a list of link names. When set, controls the behavior of the current
 393             link. When all links in the list are in an operational down state, the current link is brought
 394             down. When at least one link has carrier, the current interface is brought up.
 395             </para>
 396           </listitem>
 397         </varlistentry>
 398         <varlistentry>
 399           <term><varname>Address=</varname></term>
 400           <listitem>
 401             <para>A static IPv4 or IPv6 address and its prefix length,
 402             separated by a <literal>/</literal> character. Specify
 403             this key more than once to configure several addresses.
 404             The format of the address must be as described in
 405             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 406             This is a short-hand for an [Address] section only
 407             containing an Address key (see below). This option may be
 408             specified more than once.
 409             </para>
 410
 411             <para>If the specified address is 0.0.0.0 (for IPv4) or
 412             [::] (for IPv6), a new address range of the requested size
 413             is automatically allocated from a system-wide pool of
 414             unused ranges. The allocated range is checked against all
 415             current network interfaces and all known network
 416             configuration files to avoid address range conflicts. The
 417             default system-wide pool consists of 192.168.0.0/16,
 418             172.16.0.0/12 and 10.0.0.0/8 for IPv4, and fc00::/7 for
 419             IPv6. This functionality is useful to manage a large
 420             number of dynamically created network interfaces with the
 421             same network configuration and automatic address range
 422             assignment.</para>
 423
 424           </listitem>
 425         </varlistentry>
 426         <varlistentry>
 427           <term><varname>Gateway=</varname></term>
 428           <listitem>
 429             <para>The gateway address, which must be in the format
 430             described in
 431             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 432             This is a short-hand for a [Route] section only containing
 433             a Gateway key. This option may be specified more than
 434             once.</para>
 435           </listitem>
 436         </varlistentry>
 437         <varlistentry>
 438           <term><varname>DNS=</varname></term>
 439           <listitem>
 440             <para>A DNS server address, which must be in the format
 441             described in
 442             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 443             This option may be specified more than once. This setting is read by
 444             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 445           </listitem>
 446         </varlistentry>
 447         <varlistentry>
 448           <term><varname>Domains=</varname></term>
 449           <listitem>
 450             <para>The domains used for DNS host name resolution on this link. Takes a list of DNS domain names which
 451             are used as search suffixes for extending single-label host names (host names containing no dots) to become
 452             fully qualified domain names (FQDNs). If a single-label host name is resolved on this interface, each of
 453             the specified search domains are appended to it in turn, converting it into a fully qualified domain name,
 454             until one of them may be successfully resolved.</para>
 455
 456             <para>The specified domains are also used for routing of DNS queries: look-ups for host names ending in the
 457             domains specified here are preferably routed to the DNS servers configured for this interface. If a domain
 458             name is prefixed with <literal>~</literal>, the domain name becomes a pure "routing" domain, is used for
 459             DNS query routing purposes only and is not used in the described domain search logic. By specifying a
 460             routing domain of <literal>~.</literal> (the tilde indicating definition of a routing domain, the dot
 461             referring to the DNS root domain which is the implied suffix of all valid DNS names) it is possible to
 462             route all DNS traffic preferably to the DNS server specified for this interface. The route domain logic is
 463             particularly useful on multi-homed hosts with DNS servers serving particular private DNS zones on each
 464             interface.</para>
 465
 466             <para>This setting is read by
 467             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 468           </listitem>
 469         </varlistentry>
 470         <varlistentry>
 471           <term><varname>NTP=</varname></term>
 472           <listitem>
 473             <para>An NTP server address. This option may be specified more than once. This setting is read by
 474             <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 475           </listitem>
 476         </varlistentry>
 477         <varlistentry>
 478           <term><varname>IPForward=</varname></term>
 479           <listitem><para>Configures IP packet forwarding for the
 480           system. If enabled, incoming packets on any network
 481           interface will be forwarded to any other interfaces
 482           according to the routing table. Takes either a boolean
 483           argument, or the values <literal>ipv4</literal> or
 484           <literal>ipv6</literal>, which only enable IP packet
 485           forwarding for the specified address family.  This controls
 486           the <filename>net.ipv4.ip_forward</filename> and
 487           <filename>net.ipv6.conf.all.forwarding</filename> sysctl
 488           options of the network interface (see <ulink
 489           url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>
 490           for details about sysctl options). Defaults to
 491           <literal>no</literal>.</para>
 492
 493           <para>Note: this setting controls a global kernel option,
 494           and does so one way only: if a network that has this setting
 495           enabled is set up the global setting is turned on.  However,
 496           it is never turned off again, even after all networks with
 497           this setting enabled are shut down again.</para>
 498
 499           <para>To allow IP packet forwarding only between specific
 500           network interfaces use a firewall.</para>
 501           </listitem>
 502         </varlistentry>
 503         <varlistentry>
 504           <term><varname>IPMasquerade=</varname></term>
 505           <listitem><para>Configures IP masquerading for the network
 506           interface. If enabled, packets forwarded from the network
 507           interface will be appear as coming from the local host.
 508           Takes a boolean argument. Implies
 509           <varname>IPForward=ipv4</varname>. Defaults to
 510           <literal>no</literal>.</para></listitem>
 511         </varlistentry>
 512         <varlistentry>
 513           <term><varname>IPv6PrivacyExtensions=</varname></term>
 514           <listitem><para>Configures use of stateless temporary
 515           addresses that change over time (see <ulink
 516           url="https://tools.ietf.org/html/rfc4941">RFC 4941</ulink>,
 517           Privacy Extensions for Stateless Address Autoconfiguration
 518           in IPv6). Takes a boolean or the special values
 519           <literal>prefer-public</literal> and
 520           <literal>kernel</literal>. When true, enables the privacy
 521           extensions and prefers temporary addresses over public
 522           addresses. When <literal>prefer-public</literal>, enables the
 523           privacy extensions, but prefers public addresses over
 524           temporary addresses. When false, the privacy extensions
 525           remain disabled. When <literal>kernel</literal>, the kernel's
 526           default setting will be left in place.  Defaults to
 527           <literal>no</literal>.</para></listitem>
 528         </varlistentry>
 529         <varlistentry>
 530           <term><varname>IPv6AcceptRA=</varname></term>
 531           <listitem><para>Enable or disable IPv6 Router Advertisement (RA) reception support for the interface.  Takes
 532           a boolean parameter. If true, RAs are accepted; if false, RAs are ignored, independently of the local
 533           forwarding state. When not set, the kernel default is used, and RAs are accepted only when local forwarding
 534           is disabled for that interface.  When RAs are accepted, they may trigger the start of the DHCPv6 client if
 535           the relevant flags are set in the RA data, or if no routers are found on the link.</para>
 536
 537           <para>Further settings for the IPv6 RA support may be configured in the
 538           <literal>[IPv6AcceptRA]</literal> section, see below.</para>
 539
 540           <para>Also see <ulink
 541           url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink> in the kernel
 542           documentation regarding <literal>accept_ra</literal>, but note that systemd's setting of
 543           <constant>1</constant> (i.e. true) corresponds to kernel's setting of <constant>2</constant>.</para>
 544         </listitem>
 545         </varlistentry>
 546         <varlistentry>
 547           <term><varname>IPv6DuplicateAddressDetection=</varname></term>
 548           <listitem><para>Configures the amount of IPv6 Duplicate
 549           Address Detection (DAD) probes to send. Defaults to unset.
 550         </para></listitem>
 551         </varlistentry>
 552         <varlistentry>
 553           <term><varname>IPv6HopLimit=</varname></term>
 554           <listitem><para>Configures IPv6 Hop Limit. For each router that
 555           forwards the packet, the hop limit is decremented by 1. When the
 556           hop limit field reaches zero, the packet is discarded.
 557           Defaults to unset.
 558         </para></listitem>
 559         </varlistentry>
 560         <varlistentry>
 561           <term><varname>ProxyARP=</varname></term>
 562           <listitem><para>A boolean. Configures proxy ARP. Proxy ARP is the technique in which one host,
 563           usually a router, answers ARP requests intended for another machine. By "faking" its identity,
 564           the router accepts responsibility for routing packets to the "real" destination. (see <ulink
 565           url="https://tools.ietf.org/html/rfc1027">RFC 1027</ulink>.
 566           Defaults to unset.
 567         </para></listitem>
 568         </varlistentry>
 569         <varlistentry>
 570           <term><varname>Bridge=</varname></term>
 571           <listitem>
 572             <para>The name of the bridge to add the link to.</para>
 573           </listitem>
 574         </varlistentry>
 575         <varlistentry>
 576           <term><varname>Bond=</varname></term>
 577           <listitem>
 578             <para>The name of the bond to add the link to.</para>
 579           </listitem>
 580         </varlistentry>
 581         <varlistentry>
 582           <term><varname>VRF=</varname></term>
 583           <listitem>
 584             <para>The name of the VRF to add the link to.</para>
 585           </listitem>
 586         </varlistentry>
 587         <varlistentry>
 588           <term><varname>VLAN=</varname></term>
 589           <listitem>
 590             <para>The name of a VLAN to create on the link. This
 591             option may be specified more than once.</para>
 592           </listitem>
 593         </varlistentry>
 594         <varlistentry>
 595           <term><varname>MACVLAN=</varname></term>
 596           <listitem>
 597             <para>The name of a MACVLAN to create on the link. This
 598             option may be specified more than once.</para>
 599           </listitem>
 600         </varlistentry>
 601         <varlistentry>
 602           <term><varname>VXLAN=</varname></term>
 603           <listitem>
 604             <para>The name of a VXLAN to create on the link. This
 605             option may be specified more than once.</para>
 606           </listitem>
 607         </varlistentry>
 608         <varlistentry>
 609           <term><varname>Tunnel=</varname></term>
 610           <listitem>
 611             <para>The name of a Tunnel to create on the link. This
 612             option may be specified more than once.</para>
 613           </listitem>
 614         </varlistentry>
 615       </variablelist>
 616
 617   </refsect1>
 618
 619   <refsect1>
 620     <title>[Address] Section Options</title>
 621
 622       <para>An <literal>[Address]</literal> section accepts the
 623       following keys. Specify several <literal>[Address]</literal>
 624       sections to configure several addresses.</para>
 625
 626       <variablelist class='network-directives'>
 627         <varlistentry>
 628           <term><varname>Address=</varname></term>
 629           <listitem>
 630             <para>As in the <literal>[Network]</literal> section. This
 631             key is mandatory.</para>
 632           </listitem>
 633         </varlistentry>
 634         <varlistentry>
 635           <term><varname>Peer=</varname></term>
 636           <listitem>
 637             <para>The peer address in a point-to-point connection.
 638             Accepts the same format as the <literal>Address</literal>
 639             key.</para>
 640           </listitem>
 641         </varlistentry>
 642         <varlistentry>
 643           <term><varname>Broadcast=</varname></term>
 644           <listitem>
 645             <para>The broadcast address, which must be in the format
 646             described in
 647             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 648             This key only applies to IPv4 addresses. If it is not
 649             given, it is derived from the <literal>Address</literal>
 650             key.</para>
 651           </listitem>
 652         </varlistentry>
 653         <varlistentry>
 654           <term><varname>Label=</varname></term>
 655           <listitem>
 656             <para>An address label.</para>
 657           </listitem>
 658         </varlistentry>
 659         <varlistentry>
 660           <term><varname>PreferredLifetime=</varname></term>
 661           <listitem>
 662             <para>Allows the default "preferred lifetime" of the address to be overridden.
 663             Only three settings are accepted: <literal>forever</literal> or <literal>infinity</literal>
 664             which is the default and means that the address never expires, and <literal>0</literal> which means
 665             that the address is considered immediately "expired" and will not be used,
 666             unless explicitly requested. A setting of PreferredLifetime=0 is useful for
 667             addresses which are added to be used only by a specific application,
 668             which is then configured to use them explicitly.</para>
 669           </listitem>
 670         </varlistentry>
 671       </variablelist>
 672   </refsect1>
 673
 674   <refsect1>
 675     <title>[Route] Section Options</title>
 676       <para>The <literal>[Route]</literal> section accepts the
 677       following keys. Specify several <literal>[Route]</literal>
 678       sections to configure several routes.</para>
 679
 680       <variablelist class='network-directives'>
 681         <varlistentry>
 682           <term><varname>Gateway=</varname></term>
 683           <listitem>
 684             <para>As in the <literal>[Network]</literal> section.</para>
 685           </listitem>
 686         </varlistentry>
 687         <varlistentry>
 688           <term><varname>Destination=</varname></term>
 689           <listitem>
 690             <para>The destination prefix of the route. Possibly
 691             followed by a slash and the prefix length. If omitted, a
 692             full-length host route is assumed.</para>
 693           </listitem>
 694         </varlistentry>
 695         <varlistentry>
 696           <term><varname>Source=</varname></term>
 697           <listitem>
 698             <para>The source prefix of the route. Possibly followed by
 699             a slash and the prefix length. If omitted, a full-length
 700             host route is assumed.</para>
 701           </listitem>
 702         </varlistentry>
 703         <varlistentry>
 704           <term><varname>Metric=</varname></term>
 705           <listitem>
 706             <para>The metric of the route (an unsigned integer).</para>
 707           </listitem>
 708         </varlistentry>
 709         <varlistentry>
 710           <term><varname>Scope=</varname></term>
 711           <listitem>
 712             <para>The scope of the route, which can be <literal>global</literal>,
 713             <literal>link</literal> or <literal>host</literal>. Defaults to
 714             <literal>global</literal>.</para>
 715           </listitem>
 716         </varlistentry>
 717         <varlistentry>
 718           <term><varname>PreferredSource=</varname></term>
 719           <listitem>
 720             <para>The preferred source address of the route. The address
 721             must be in the format described in
 722             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 723           </listitem>
 724         </varlistentry>
 725         <varlistentry>
 726           <term><varname>Table=<replaceable>num</replaceable></varname></term>
 727           <listitem>
 728           <para>The table identifier for the route (a number between 1 and 4294967295, or 0 to unset).
 729           The table can be retrieved using <command>ip route show table <replaceable>num</replaceable></command>.
 730           </para>
 731           </listitem>
 732         </varlistentry>
 733       </variablelist>
 734   </refsect1>
 735
 736   <refsect1>
 737     <title>[DHCP] Section Options</title>
 738       <para>The <literal>[DHCP]</literal> section configures the
 739       DHCPv4 and DHCP6 client, if it is enabled with the
 740       <varname>DHCP=</varname> setting described above:</para>
 741
 742       <variablelist class='network-directives'>
 743         <varlistentry>
 744           <term><varname>UseDNS=</varname></term>
 745           <listitem>
 746             <para>When true (the default), the DNS servers received
 747             from the DHCP server will be used and take precedence over
 748             any statically configured ones.</para>
 749
 750             <para>This corresponds to the <option>nameserver</option>
 751             option in <citerefentry
 752             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 753           </listitem>
 754         </varlistentry>
 755         <varlistentry>
 756           <term><varname>UseNTP=</varname></term>
 757           <listitem>
 758             <para>When true (the default), the NTP servers received
 759             from the DHCP server will be used by systemd-timesyncd
 760             and take precedence over any statically configured ones.</para>
 761           </listitem>
 762         </varlistentry>
 763         <varlistentry>
 764           <term><varname>UseMTU=</varname></term>
 765           <listitem>
 766             <para>When true, the interface maximum transmission unit
 767             from the DHCP server will be used on the current link.
 768             Defaults to false.</para>
 769           </listitem>
 770         </varlistentry>
 771         <varlistentry>
 772           <term><varname>SendHostname=</varname></term>
 773           <listitem>
 774             <para>When true (the default), the machine's hostname will
 775             be sent to the DHCP server.</para>
 776           </listitem>
 777         </varlistentry>
 778         <varlistentry>
 779           <term><varname>UseHostname=</varname></term>
 780           <listitem>
 781             <para>When true (the default), the hostname received from
 782             the DHCP server will be set as the transient hostname of the system
 783             </para>
 784           </listitem>
 785         </varlistentry>
 786         <varlistentry>
 787         <term><varname>Hostname=</varname></term>
 788         <listitem>
 789           <para>Use this value for the hostname which is sent to the
 790           DHCP server, instead of machine's hostname.</para>
 791         </listitem>
 792       </varlistentry>
 793         <varlistentry>
 794           <term><varname>UseDomains=</varname></term>
 795           <listitem>
 796             <para>Takes a boolean argument, or the special value <literal>route</literal>. When true, the domain name
 797             received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
 798             the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name received from
 799             the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
 800             the <option>Domains=</option> setting when the argument is prefixed with <literal>~</literal>. Defaults to
 801             false.</para>
 802
 803             <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
 804             of all host names, in particular of single-label names. It is generally safer to use the supplied domain
 805             only as routing domain, rather than as search domain, in order to not have it affect local resolution of
 806             single-label names.</para>
 807
 808             <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
 809             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 810           </listitem>
 811         </varlistentry>
 812         <varlistentry>
 813           <term><varname>UseRoutes=</varname></term>
 814           <listitem>
 815             <para>When true (the default), the static routes will be
 816             requested from the DHCP server and added to the routing
 817             table with a metric of 1024.</para>
 818           </listitem>
 819         </varlistentry>
 820
 821         <varlistentry>
 822           <term><varname>UseTimezone=</varname></term>
 823
 824           <listitem><para>When true, the timezone received from the
 825           DHCP server will be set as timezone of the local
 826           system. Defaults to <literal>no</literal>.</para></listitem>
 827         </varlistentry>
 828
 829         <varlistentry>
 830           <term><varname>CriticalConnection=</varname></term>
 831           <listitem>
 832             <para>When true, the connection will never be torn down
 833             even if the DHCP lease expires. This is contrary to the
 834             DHCP specification, but may be the best choice if, say,
 835             the root filesystem relies on this connection. Defaults to
 836             false.</para>
 837           </listitem>
 838         </varlistentry>
 839
 840         <varlistentry>
 841           <term><varname>ClientIdentifier=</varname></term>
 842           <listitem>
 843             <para>The DHCPv4 client identifier to use. Either <literal>mac</literal> to use the MAC address of the link
 844             or <literal>duid</literal> (the default, see below) to use an RFC4361-compliant Client ID.</para>
 845           </listitem>
 846         </varlistentry>
 847
 848         <varlistentry>
 849           <term><varname>VendorClassIdentifier=</varname></term>
 850           <listitem>
 851             <para>The vendor class identifier used to identify vendor
 852             type and configuration.</para>
 853           </listitem>
 854         </varlistentry>
 855
 856         <varlistentry>
 857           <term><varname>DUIDType=</varname></term>
 858           <listitem>
 859             <para>Override the global <varname>DUIDType</varname> setting for this network. See
 860             <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 861             for a description of possible values.</para>
 862           </listitem>
 863         </varlistentry>
 864
 865         <varlistentry>
 866           <term><varname>DUIDRawData=</varname></term>
 867           <listitem>
 868             <para>Override the global <varname>DUIDRawData</varname> setting for this network. See
 869             <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 870             for a description of possible values.</para>
 871           </listitem>
 872         </varlistentry>
 873
 874         <varlistentry>
 875           <term><varname>IAID=</varname></term>
 876           <listitem>
 877             <para>The DHCP Identity Association Identifier (IAID) for the interface, a 32-bit unsigned integer.</para>
 878           </listitem>
 879         </varlistentry>
 880
 881         <varlistentry>
 882           <term><varname>RequestBroadcast=</varname></term>
 883           <listitem>
 884             <para>Request the server to use broadcast messages before
 885             the IP address has been configured. This is necessary for
 886             devices that cannot receive RAW packets, or that cannot
 887             receive packets at all before an IP address has been
 888             configured. On the other hand, this must not be enabled on
 889             networks where broadcasts are filtered out.</para>
 890           </listitem>
 891         </varlistentry>
 892
 893         <varlistentry>
 894           <term><varname>RouteMetric=</varname></term>
 895           <listitem>
 896             <para>Set the routing metric for routes specified by the
 897             DHCP server.</para>
 898           </listitem>
 899         </varlistentry>
 900       </variablelist>
 901     </refsect1>
 902
 903   <refsect1>
 904     <title>[IPv6AcceptRA] Section Options</title>
 905       <para>The <literal>[IPv6AcceptRA]</literal> section configures the IPv6 Router Advertisement
 906       (RA) client, if it is enabled with the <varname>IPv6AcceptRA=</varname> setting described
 907       above:</para>
 908
 909       <variablelist class='network-directives'>
 910         <varlistentry>
 911           <term><varname>UseDNS=</varname></term>
 912           <listitem>
 913             <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
 914             precedence over any statically configured ones.</para>
 915
 916             <para>This corresponds to the <option>nameserver</option> option in <citerefentry
 917             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 918           </listitem>
 919         </varlistentry>
 920
 921         <varlistentry>
 922           <term><varname>UseDomains=</varname></term>
 923           <listitem>
 924             <para>Takes a boolean argument, or the special value <literal>route</literal>. When true, the domain name
 925             received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
 926             the effect of the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name
 927             received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
 928             effect of the <option>Domains=</option> setting when the argument is prefixed with
 929             <literal>~</literal>. Defaults to false.</para>
 930
 931             <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
 932             of all host names, in particular of single-label names. It is generally safer to use the supplied domain
 933             only as routing domain, rather than as search domain, in order to not have it affect local resolution of
 934             single-label names.</para>
 935
 936             <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
 937             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 938           </listitem>
 939         </varlistentry>
 940       </variablelist>
 941   </refsect1>
 942
 943
 944   <refsect1>
 945     <title>[DHCPServer] Section Options</title>
 946     <para>The <literal>[DHCPServer]</literal> section contains
 947     settings for the DHCP server, if enabled via the
 948     <varname>DHCPServer=</varname> option described above:</para>
 949
 950     <variablelist class='network-directives'>
 951
 952       <varlistentry>
 953         <term><varname>PoolOffset=</varname></term>
 954         <term><varname>PoolSize=</varname></term>
 955
 956         <listitem><para>Configures the pool of addresses to hand out. The pool
 957         is a contiguous sequence of IP addresses in the subnet configured for
 958         the server address, which does not include the subnet nor the broadcast
 959         address. <varname>PoolOffset=</varname> takes the offset of the pool
 960         from the start of subnet, or zero to use the default value.
 961         <varname>PoolSize=</varname> takes the number of IP addresses in the
 962         pool or zero to use the default value. By default, the pool starts at
 963         the first address after the subnet address and takes up the rest of
 964         the subnet, excluding the broadcast address. If the pool includes
 965         the server address (the default), this is reserved and not handed
 966         out to clients.</para></listitem>
 967       </varlistentry>
 968
 969       <varlistentry>
 970         <term><varname>DefaultLeaseTimeSec=</varname></term>
 971         <term><varname>MaxLeaseTimeSec=</varname></term>
 972
 973         <listitem><para>Control the default and maximum DHCP lease
 974         time to pass to clients. These settings take time values in seconds or
 975         another common time unit, depending on the suffix. The default
 976         lease time is used for clients that did not ask for a specific
 977         lease time. If a client asks for a lease time longer than the
 978         maximum lease time, it is automatically shortened to the
 979         specified time. The default lease time defaults to 1h, the
 980         maximum lease time to 12h. Shorter lease times are beneficial
 981         if the configuration data in DHCP leases changes frequently
 982         and clients shall learn the new settings with shorter
 983         latencies. Longer lease times reduce the generated DHCP
 984         network traffic.</para></listitem>
 985       </varlistentry>
 986
 987       <varlistentry>
 988         <term><varname>EmitDNS=</varname></term>
 989         <term><varname>DNS=</varname></term>
 990
 991         <listitem><para>Configures whether the DHCP leases handed out
 992         to clients shall contain DNS server information. The
 993         <varname>EmitDNS=</varname> setting takes a boolean argument
 994         and defaults to <literal>yes</literal>. The DNS servers to
 995         pass to clients may be configured with the
 996         <varname>DNS=</varname> option, which takes a list of IPv4
 997         addresses. If the <varname>EmitDNS=</varname> option is
 998         enabled but no servers configured, the servers are
 999         automatically propagated from an "uplink" interface that has
1000         appropriate servers set. The "uplink" interface is determined
1001         by the default route of the system with the highest
1002         priority. Note that this information is acquired at the time
1003         the lease is handed out, and does not take uplink interfaces
1004         into account that acquire DNS or NTP server information at a
1005         later point. DNS server propagation does not take
1006         <filename>/etc/resolv.conf</filename> into account. Also, note
1007         that the leases are not refreshed if the uplink network
1008         configuration changes. To ensure clients regularly acquire the
1009         most current uplink DNS server information, it is thus
1010         advisable to shorten the DHCP lease time via
1011         <varname>MaxLeaseTimeSec=</varname> described
1012         above.</para></listitem>
1013       </varlistentry>
1014
1015       <varlistentry>
1016         <term><varname>EmitNTP=</varname></term>
1017         <term><varname>NTP=</varname></term>
1018
1019         <listitem><para>Similar to the <varname>EmitDNS=</varname> and
1020         <varname>DNS=</varname> settings described above, these
1021         settings configure whether and what NTP server information
1022         shall be emitted as part of the DHCP lease. The same syntax,
1023         propagation semantics and defaults apply as for
1024         <varname>EmitDNS=</varname> and
1025         <varname>DNS=</varname>.</para></listitem>
1026       </varlistentry>
1027
1028       <varlistentry>
1029         <term><varname>EmitRouter=</varname></term>
1030
1031         <listitem><para>Similar to the <varname>EmitDNS=</varname>
1032         setting described above, this setting configures whether the
1033         DHCP lease should contain the router option. The same syntax,
1034         propagation semantics and defaults apply as for
1035         <varname>EmitDNS=</varname>.</para></listitem>
1036       </varlistentry>
1037
1038       <varlistentry>
1039         <term><varname>EmitTimezone=</varname></term>
1040         <term><varname>Timezone=</varname></term>
1041
1042         <listitem><para>Configures whether the DHCP leases handed out
1043         to clients shall contain timezone information. The
1044         <varname>EmitTimezone=</varname> setting takes a boolean
1045         argument and defaults to <literal>yes</literal>. The
1046         <varname>Timezone=</varname> setting takes a timezone string
1047         (such as <literal>Europe/Berlin</literal> or
1048         <literal>UTC</literal>) to pass to clients. If no explicit
1049         timezone is set, the system timezone of the local host is
1050         propagated, as determined by the
1051         <filename>/etc/localtime</filename> symlink.</para></listitem>
1052       </varlistentry>
1053
1054     </variablelist>
1055   </refsect1>
1056
1057   <refsect1>
1058     <title>[Bridge] Section Options</title>
1059       <para>The <literal>[Bridge]</literal> section accepts the
1060       following keys.</para>
1061       <variablelist class='network-directives'>
1062         <varlistentry>
1063           <term><varname>UnicastFlood=</varname></term>
1064           <listitem>
1065             <para>A boolean. Controls whether the bridge should flood
1066             traffic for which an FDB entry is missing and the destination
1067             is unknown through this port. Defaults to on.
1068             </para>
1069           </listitem>
1070         </varlistentry>
1071         <varlistentry>
1072           <term><varname>HairPin=</varname></term>
1073           <listitem>
1074             <para>A boolean. Configures whether traffic may be sent back
1075             out of the port on which it was received. By default, this
1076             flag is false, and the bridge will not forward traffic back
1077             out of the receiving port.</para>
1078           </listitem>
1079         </varlistentry>
1080         <varlistentry>
1081           <term><varname>UseBPDU=</varname></term>
1082           <listitem>
1083             <para>A boolean. Configures whether STP Bridge Protocol Data Units will be
1084             processed by the bridge port. Defaults to yes.</para>
1085           </listitem>
1086         </varlistentry>
1087         <varlistentry>
1088           <term><varname>FastLeave=</varname></term>
1089           <listitem>
1090             <para>A boolean. This flag allows the bridge to immediately stop multicast
1091             traffic on a port that receives an IGMP Leave message. It is only used with
1092             IGMP snooping if enabled on the bridge. Defaults to off.</para>
1093           </listitem>
1094         </varlistentry>
1095         <varlistentry>
1096           <term><varname>AllowPortToBeRoot=</varname></term>
1097           <listitem>
1098             <para>A boolean. Configures whether a given port is allowed to
1099             become a root port. Only used when STP is enabled on the bridge.
1100             Defaults to on.</para>
1101           </listitem>
1102         </varlistentry>
1103         <varlistentry>
1104           <term><varname>Cost=</varname></term>
1105           <listitem>
1106             <para>Sets the "cost" of sending packets of this interface.
1107             Each port in a bridge may have a different speed and the cost
1108             is used to decide which link to use. Faster interfaces
1109             should have lower costs.</para>
1110           </listitem>
1111         </varlistentry>
1112       </variablelist>
1113   </refsect1>
1114   <refsect1>
1115     <title>[BridgeFDB] Section Options</title>
1116       <para>The <literal>[BridgeFDB]</literal> section manages the
1117       forwarding database table of a port and accepts the following
1118       keys. Specify several <literal>[BridgeFDB]</literal> sections to
1119       configure several static MAC table entries.</para>
1120
1121       <variablelist class='network-directives'>
1122         <varlistentry>
1123           <term><varname>MACAddress=</varname></term>
1124           <listitem>
1125             <para>As in the <literal>[Network]</literal> section. This
1126             key is mandatory.</para>
1127           </listitem>
1128         </varlistentry>
1129         <varlistentry>
1130           <term><varname>VLANId=</varname></term>
1131           <listitem>
1132             <para>The VLAN ID for the new static MAC table entry. If
1133             omitted, no VLAN ID info is appended to the new static MAC
1134             table entry.</para>
1135           </listitem>
1136         </varlistentry>
1137       </variablelist>
1138   </refsect1>
1139   <refsect1>
1140     <title>[BridgeVLAN] Section Options</title>
1141       <para>The <literal>[BridgeVLAN]</literal> section manages the VLAN ID configuration of a bridge port and accepts
1142       the following keys. Specify several <literal>[BridgeVLAN]</literal> sections to configure several VLAN entries.
1143       The <varname>VLANFiltering=</varname> option has to be enabled, see <literal>[Bridge]</literal> section in
1144       <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
1145
1146       <variablelist class='network-directives'>
1147         <varlistentry>
1148           <term><varname>VLAN=</varname></term>
1149           <listitem>
1150             <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
1151             from 1 to 4094.</para>
1152           </listitem>
1153         </varlistentry>
1154         <varlistentry>
1155           <term><varname>EgressUntagged=</varname></term>
1156           <listitem>
1157             <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
1158             <varname>EgressUntagged=</varname> implicates the use of <varname>VLAN=</varname> above and will enable the
1159             VLAN ID for ingress as well. This can be either a single ID or a range M-N.</para>
1160           </listitem>
1161         </varlistentry>
1162         <varlistentry>
1163           <term><varname>PVID=</varname></term>
1164           <listitem>
1165             <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
1166             <varname>PVID=</varname> can be used only once. Configuring <varname>PVID=</varname> implicates the use of
1167             <varname>VLAN=</varname> above and will enable the VLAN ID for ingress as well.</para>
1168           </listitem>
1169         </varlistentry>
1170       </variablelist>
1171   </refsect1>
1172
1173   <refsect1>
1174     <title>Example</title>
1175     <example>
1176       <title>/etc/systemd/network/50-static.network</title>
1177
1178       <programlisting>[Match]
1179 Name=enp2s0
1180
1181 [Network]
1182 Address=192.168.0.15/24
1183 Gateway=192.168.0.1</programlisting>
1184     </example>
1185
1186     <example>
1187       <title>/etc/systemd/network/80-dhcp.network</title>
1188
1189       <programlisting>[Match]
1190 Name=en*
1191
1192 [Network]
1193 DHCP=yes</programlisting>
1194     </example>
1195
1196     <example>
1197       <title>/etc/systemd/network/25-bridge-static.network</title>
1198
1199       <programlisting>[Match]
1200 Name=bridge0
1201
1202 [Network]
1203 Address=192.168.0.15/24
1204 Gateway=192.168.0.1
1205 DNS=192.168.0.1</programlisting>
1206     </example>
1207
1208     <example>
1209       <title>/etc/systemd/network/25-bridge-slave-interface.network</title>
1210
1211       <programlisting>[Match]
1212 Name=enp2s0
1213
1214 [Network]
1215 Bridge=bridge0</programlisting>
1216     </example>
1217     <example>
1218       <title>/etc/systemd/network/25-bridge-slave-interface-vlan.network</title>
1219
1220       <programlisting>[Match]
1221 Name=enp2s0
1222
1223 [Network]
1224 Bridge=bridge0
1225
1226 [BridgeVLAN]
1227 VLAN=1-32
1228 PVID=42
1229 EgressUntagged=42
1230
1231 [BridgeVLAN]
1232 VLAN=100-200
1233
1234 [BridgeVLAN]
1235 EgressUntagged=300-400</programlisting>
1236     </example>
1237     <example>
1238       <title>/etc/systemd/network/25-ipip.network</title>
1239
1240       <programlisting>[Match]
1241 Name=em1
1242
1243 [Network]
1244 Tunnel=ipip-tun</programlisting>
1245     </example>
1246
1247     <example>
1248       <title>/etc/systemd/network/25-sit.network</title>
1249
1250       <programlisting>[Match]
1251 Name=em1
1252
1253 [Network]
1254 Tunnel=sit-tun</programlisting>
1255     </example>
1256
1257     <example>
1258       <title>/etc/systemd/network/25-gre.network</title>
1259
1260       <programlisting>[Match]
1261 Name=em1
1262
1263 [Network]
1264 Tunnel=gre-tun</programlisting>
1265     </example>
1266
1267     <example>
1268       <title>/etc/systemd/network/25-vti.network</title>
1269
1270       <programlisting>[Match]
1271 Name=em1
1272
1273 [Network]
1274 Tunnel=vti-tun</programlisting>
1275     </example>
1276
1277     <example>
1278       <title>/etc/systemd/network/25-bond.network</title>
1279
1280       <programlisting>[Match]
1281 Name=bond1
1282
1283 [Network]
1284 DHCP=yes
1285 </programlisting>
1286     </example>
1287
1288     <example>
1289       <title>/etc/systemd/network/25-vrf.network</title>
1290       <para>Add the bond1 interface to the VRF master interface vrf-test. This will redirect routes generated on this interface to be within the routing table defined during VRF creation. Traffic won't be redirected towards the VRFs routing table unless specific ip-rules are added.</para>
1291       <programlisting>[Match]
1292 Name=bond1
1293
1294 [Network]
1295 VRF=vrf-test
1296 </programlisting>
1297     </example>
1298
1299   </refsect1>
1300
1301   <refsect1>
1302     <title>See Also</title>
1303     <para>
1304       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1305       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1306       <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1307       <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1308       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1309     </para>
1310   </refsect1>
1311
1312 </refentry>